Abstract:

A light-emitting device is provided which uses an encapsulant material
made from a polymer having a high relative light output. The
light-emitting device includes a light-emitting element and a member
sealing the light-emitting element. The encapsulant material has one or
more than two kinds of units given by the following formula (1) and a
refractive index of 1.55 or more.
##STR00001##
where R is a hydrogen atom, alkyl group or phenyl group, Y is an alkyl
group of which the carbon number is 1 to 6 or an alkyloxy group of which
the carbon number is 1 to 6 and Z is an aromatic compound that meets
predetermined requirements.

Claims:

1. An optical component encapsulant material made from a polymer having
one or more than two kinds of units given by the following formula (1)
and a refractive index of 1.55 or more: ##STR00011## where R is a
hydrogen atom, alkyl group or phenyl group, Y is an alkyl group of which
the carbon number is 1 to 6 or an alkyloxy group of which the carbon
number is 1 to 6, Z is one of functional groups given by the following
formulas (2) to (7) in which Z can be bonded to Y in all possible
positions: ##STR00012##

2. The optical component encapsulant material according to claim 1,
wherein the refractive index is 1.55 to 1.65.

3. The optical component encapsulant material according to claim 1,
wherein Y is --CH2--CH2--CH2-- or
--CH2--CH2--CH2--O--.

4. A light-emitting device comprising:a light-emitting element; anda
member sealing the light-emitting element,wherein the encapsulant
material having one or more than two kinds of units given by the
following formula (1) and a refractive index of 1.55 or more:
##STR00013## where R is a hydrogen atom, alkyl group or phenyl group, Y
is an alkyl group of which the carbon number is 1 to 6 or an alkyloxy
group of which the carbon number is 1 to 6 and Z is one of functional
groups given by the following formulas (2) to (7) in which Z can be
bonded to Y in all possible positions: ##STR00014##

5. The light-emitting device according to claim 4, wherein the refractive
index is 1.55 to 1.65.

6. The light-emitting device according to claim 4, wherein the
light-emitting element has an InGaN layer mounted on a substrate.

7. The light-emitting device according to claim 4, wherein Y is
--CH2--CH2--CH2-- or --CH2--CH2--CH2--O--.

Description:

TECHNICAL FIELD

[0001]The present invention relates to an optical component encapsulant
material having color fastness, heat resistance and a high relative light
output, and a light-emitting device.

[0002]This application claims the priority of the Japanese Patent
Application No. 2007-205939 filed in the Japanese Patent Office on Aug.
7, 2007, the entirety of which is incorporated by reference herein.

BACKGROUND ART

[0003]LEDs (light-emitting diode) have lately been used widely as an
illuminator, light source for a projector, backlight of liquid crystal
television, etc. Since the LED dissipates no excessive heat and has an
overwhelmingly long life, it attracts more attention because of its
possibility of replacing the fluorescent lamp in future. Among others,
the practical application of the blue LED has led to development of
LED-based signals, full-color LED display devices, etc. and such
LED-based products have rapidly become popular. Along with such
prevalence of the LED products, it is more and more demanded to improve
the performance of the LED.

[0004]There is disclosed in the Japanese Published Unexamined Patent
Application No. 2002-80733 (Patent Document 1), for example, an LED
encapsulant material made from a composition containing, as critical
components, an organic compound made up of an organic skeleton containing
at least two carbon-carbon double bonds reactive with SiH group in one
molecule, a silicide compound containing at least two SiH groups in one
molecule and a hydrosilylated catalyst and which thus has a high heat
resistance, low birefringence, small photoelastic coefficient, improved
transparency and high toughness.

[0005]Also there is disclosed in the Japanese Published Unexamined Patent
Application No. 2002-317048 (Patent Document 2), for example, an LED
encapsulant material made from an aliphatic organic compound having at
least two carbon-carbon double bonds reactive with SiH group and one to
six vinyl groups and of which the molecular weight is under 900 and
viscosity is under 1000 P (poises), a hardener produced by
hydrosilylating a chain and/or cyclic polyorganosiloxane having at least
two SiH groups and which thus has at least two SiH groups or an organic
compound given by the following formula (1), and a hardenable compound
produced by hydrosilylating a cyclic polyorganosiloxane having at least
two SiH groups and which thus has at least two SiH groups:

##STR00002##

where R1 indicates a univalent organic group whose carbon number is 1
to 50; these R1 may be different from or equal to each other.

DISCLOSURE OF THE INVENTION

Problems to be Solved by the Invention

[0006]Among the demands for improved performances of the LED-based
light-emitting device (will be referred to as "LED device" hereafter),
the one for higher luminance is growing. For higher luminance of the LED
device, it is necessary to improve the relative light output of an
encapsulant material for the LED device.

[0007]In FIG. 1, there is shown the relation between the refractive index
and relative light output (%) of an encapsulant material for a commercial
LED device in which sapphire (of which the refractive index n=1.76) is
used as the substrate of an LED chip. In FIG. 1, each of points P1,
P2, P3 and P4 indicate a relative light output (%) plotted
in relation to the refractive index of the commercial encapsulant
material in the LED device in case the relative light output for the
refractive index (n=1.76) of the sapphire substrate is taken as 100%. As
shown in FIG. 1, the relative light output of an encapsulant material is
nearly proportional to the refractive index n of the encapsulant material
and as the refractive index n is higher, the relative light output (%) is
higher. Generally, in a linear range between P3 and P4, the
relative light output of an encapsulant material made from a commercial
silicone (will be referred to as "polysiloxane" hereafter) is 60 to 75%
for a refractive index of 1.4 to 1.5. For a high relative light output
between Q1 and Q2, the encapsulant material should desirably be
made from a polymer having a high refractive index, for example.

[0008]One of the methods of increasing the refractive index of an
encapsulant material is to introduce a benzene ring into the side chain
of a polymer used to form the encapsulant material, for example. In this
case, the polymer has a high refractive index but drastically turns
yellow. Among others, acrylic resin is easily decomposed since it has an
ester bond and carbonyl group. On the other hand, a polysiloxane being a
polymer having a siloxane bond as the skeleton is not easily decomposed
because it has a large bonding energy of Si--O (Si--O: 444 kJ/mol).
However, even a polysiloxane having a phenyl group introduced in the side
chain thereof is transparent but low in refractive index.

[0009]FIG. 2 shows the relation between heat resistance, light resistance
and refractive index of an acrylic resin (S1), epoxy resin
(S2), polyphenylmethylsiloxane (S3) and polydimethylsiloxane
(S4) each as an encapsulant material to be used in the conventional
LED device. As shown in FIG. 2, the acrylic resin (S1) and the epoxy
resin (S2) are high in refractive index but inferior in heat
resistance and light resistance, while the polyphenylmethylsiloxane
(S3) and polydimethylsiloxane (S4) are superior in heat
resistance and light resistance but low in refractive index.

[0010]It is therefore desirable to overcome the above-mentioned drawbacks
of the related art by providing an optical component encapsulant material
having a high color fastness, heat resistance and relative light output
and a light-emitting device.

[0011]According to an embodiment of the present invention, there is
provided an optical component encapsulant material made from a polymer
having one or more than two kinds of units given by the following formula
(2) and a refractive index of 1.55 or more:

##STR00003##

where R is a hydrogen atom, alkyl group or phenyl group, Y is an alkyl
group of which the carbon number is 1 to 6 or an alkyloxy group of which
the carbon number is 1 to 6 and Z is one of functional groups given by
the following formulas (3) to (8) in which Z can be bonded to Y in all
possible positions:

##STR00004##

[0012]According to another embodiment of the present invention, there is
provided a light-emitting device including a light-emitting element and a
member sealing the light-emitting element, the encapsulant material made
from a polymer having one or more than two kinds of units given by the
following formula (2) and a refractive index of 1.55 or more:

##STR00005##

where R is a hydrogen atom, alkyl group or phenyl group, Y is an alkyl
group of which the carbon number is 1 to 6 or an alkyloxy group of which
the carbon number is 1 to 6 and Z is one of functional groups given by
the following formulas (3) to (8) in which Z can be bonded to Y in all
possible positions:

##STR00006##

[0013]The foregoing and other features, aspects and advantages of the
present invention will become more apparent from the following detailed
description of embodiments of the present invention when taken in
conjunction with the accompanying drawings. It should be noted that the
present invention is not limited to the embodiments but can freely be
modified without departing from the scope and concept thereof defined in
the claims given later.

BRIEF DESCRIPTION OF THE DRAWINGS

[0014]FIG. 1 shows the relation between the refractive index and relative
light output (%) of an encapsulant material (polysiloxane) in a
commercial LED device.

[0015]FIG. 2 shows the relation between heat resistance, light resistance
and refractive index of an acrylic resin, epoxy resin,
polyphenylmethylsiloxane and polydimethylsiloxane each as an LED
encapsulant material.

[0016]FIG. 3 shows the construction of a light-emitting device according
to an embodiment of the present invention.

[0017]FIG. 4A shows an example of the change in luminance of a royal-blue
LED provided with an encapsulant material formed from an epoxy resin, and
FIG. 4B shows an example of the change in luminance of a royal-blue LED
provided with an encapsulant material formed from a polysiloxane.

[0018]FIG. 5 shows a change of light transmittance (%) in relation to
wavelength (nm) when light is irradiated to
poly(allyletherbiphenyl-pendant)siloxane.

BEST MODE FOR CARRYING OUT THE INVENTION

[0019]The present invention will be described in detail below concerning
embodiments thereof with reference to the accompanying drawings.

[0020]Referring now to FIG. 3, there is schematically illustrated an
example of the light-emitting device according to an embodiment of the
present invention. The light-emitting device, generally indicated with a
reference numeral 1, includes an LED (light-emitting diode) chip 11, base
12, adhesive layer 13, frame 14 joined to the base 12 via the adhesive
layer 13 being laid between them to surround the LED chip 11 and which
functions as a lens, encapsulant material 15 formed by filling a sealing
material in the frame 14 which serves as a lens (will be referred to as
"lens frame" hereafter), member 16, electroconductive gold wire 17 and an
electroconductive substrate 18.

[0021]The LED chip 11 is a light-emitting element including a
light-emitting layer 11A made from InGaN and a sapphire substrate 11B
mounted on the light-emitting layer 11A with a low-temperature buffer
layer (not shown), for example, being laid between them. The LED chip 11
emits royal-blue light of 440 to 460 nm in wavelength, for example. Also,
in the LED chip 11, the light-emitting layer 11A is mounted at the bottom
thereof on the electroconductive substrate 18 with a solder layer (not
shown) of In etc., for example, being laid between them. Also, the LED
chip 11 is joined to the base 12 with the gold wire 17 being laid between
them.

[0022]The base 12 is made from an insulative material such as plastic or
the like. The adhesive layer 13 may be made from one selected from
various materials which can join the lens frame 14 and base 12 to each
other, such as UV-curing adhesive.

[0023]The lens frame 14 may be formed from a transparent material equal in
coefficient of linear expansion to the material of the encapsulant
material 15. In this embodiment, the lens frame 14 is formed from a
cyclic olefin copolymer (COC) superior in heat resistance and strength
and having a high light transmittance. However, it should be noted that
an embodiment of the present invention is not limited to this material
but the lens frame 14 may be formed from one selected from various
materials having such properties. Also, the lens frame 14 is designed to
direct the light from the substrate 11B generally horizontally as
indicated by arrows in FIG. 3.

[0024]The member 16 may be made from a material having high heat
conduction, insulation performance, heat resistance and other superior
properties as well as being capable of preventing the LED chip 11 from
being damaged due to a difference in thermal expansion between the LED
chip 11 and heat-dissipating portion. For example, AlN or the like, which
is relatively high in thermal conduction and electrically insulative, may
be selected as the material, but it should be noted that an embodiment of
the present invention is not limited to such a material.

[0025]The electroconductive substrate 18 has the LED chip 11 mounted
thereon as shown. The electroconductive substrate 18 is made from AlN.
However, it should be noted that an embodiment of the present invention
is not limited to AlN but the material of the electroconductive substrate
18 may be made from a material which is relatively high in thermal
conduction, such as SiC, Si or the like.

[0026]Note that the LED chip 11 and electroconductive substrate 18 may be
joined to each other with a solder of SnPb, AuSn, SnAgCu or the like or a
paste of Ag or the like, for example, and more preferably with a solder
containing no lead (Pb), such as AuSn, SnAgCu or the like.

[0027]According to this embodiment, the encapsulant material 15 is made
from a material capable of putting a high-luminance LED device into
practice. That is, the sealing material should preferably be a polymer
having color fastness, heat resistance and a high relative light output
(high refractive index).

[0028]FIG. 4A shows an example of the change in luminance of a royal-blue
LED (at 350 mA and 85° C.) sealed by a member formed from an epoxy
or urethane resin, and FIG. 4B shows an example of the change in
luminance of a royal-blue LED (at 350 mA and 85° C.) sealed by a
member formed from a polysiloxane. In FIG. 4A, A1 indicates the luminance
change of the royal-blue LED sealed by an epoxy resin (NLD-SL-1107 by
SANYU REC CO., LTD.) of which the refractive index is 1.49, and A2
indicates the luminance change of the royal-blue LED sealed by a urethane
resin (H-7E11-1 by DAI-ICHI KOGYO SEIYAKU CO., LTD.) of which the
refractive index is 1.48. In FIG. 4B, B1 indicates the luminance change
of the royal-blue LED sealed by a polydimethylsiloxane (CY52-276 by TORAY
DOW) of which the refractive index is 1.41, and B2 indicates the
luminance change of the royal-blue LED sealed by a
polyphenylmethylsiloxane (XE14-C1389 by TOSHIBA GE) of which the
refractive index is 1.53.

[0029]As will be known from FIGS. 4A and 4B, the luminance of the
royal-blue LED sealed by the epoxy or urethane resin, for example, is
lower as the time elapses, while that of the royal-blue LED sealed by the
polysiloxane is not lower even with time elapse. Also, the acrylic resin
has an easily decomposable structure having a carbonyl group and ester
bond, while the polysiloxane has an extremely stable structure in which
the bonding energy of Si--O is as large as 444 kJ/mol, is highly
transparent as compared with the acrylic resin and will not turn yellow.

[0030]Thus, the encapsulant material 15 in this embodiment is made from a
polysiloxane which takes siloxane bond as the skeleton. This sealing
material should have a functional group containing an aromatic moiety in
the side chain thereof.

[0031]The material of the encapsulant material 15 should preferably have a
high relative light output. The relative light output is proportional to
the refractive index of a polymer. For a high relative light output,
there should be designed a polymer having a high refractive index. For a
high relative light output of the light-emitting device 1, the refractive
index of the material of the encapsulant material 15 should be
approximate to that of the substrate 11B. More particularly, since the
refractive index of the sapphire forming the substrate 11B is 1.74, the
refractive index of the material of the encapsulant material 15 should be
approximate to that (1.74) of the sapphire. On this account, various
functional groups are introduced as side chain into the polysiloxane main
chain for the refractive index of the material of the encapsulant
material 15 to be higher than 1.55, which is higher than ever, more
preferably, 1.55 to 1.65.

[0032]The material used to form the encapsulant material 15 may be a
polymer having one or more than two kinds of units given by the formula
(2):

##STR00007##

where R is a hydrogen atom, alkyl group or phenyl group, Y is an alkyl
group of which the carbon number is 1 to 6 or an alkyloxy group of which
the carbon number is 1 to 6, one of --(CH2)n--,
--(CH2)n--O-- and the like wherein n=1 to 6 being selectable as
Y, and Z is one of functional groups given by the following formulas (3)
to (8) in which Z can be bonded to Y in all possible positions:

##STR00008##

[0033]Tables 1 and 2 show relations between comonomer content (%) and
refractive index of a polydiphenylsiloxane-polydimethylsiloxane copolymer
having a structure given by the following formula (9) and a
polyphenylmethylsiloxane-polydimethylsiloxane copolymer having a
structure given by the following formula (10), respectively. It will be
known from Tables 1 and 2 that as the comonomer content (%) is larger,
the refractive index of the copolymer is higher. It will thus be seen
that in a polymer having a siloxane structure, as the content (%) of
phenyl group in the side chain is larger, the refractive index of the
polymer is higher.

[0034]As will be known from Table 2, a
polyphenylmethylsiloxane-polydimethylsiloxane copolymer containing
comonomer in 45 to 50% and of which the refractive index is 1.50 is
adopted as a material of the encapsulant material 15 in this embodiment.

[0035]As mentioned above, as the polysiloxane has an increased number of
the aromatic rings in the side chain thereof, the polymer refractive
index is higher. It should be noted however that the number of the
aromatic rings the polysiloxane used to form the encapsulant material 15
has in the side chain should necessary be 1 to 3 in the units of the
polysiloxane. If the number of aromatic rings in the units of the
polysiloxane is 4 or more, the polysiloxane turns yellow and is not
suitable for use to form an encapsulant material which should be highly
transparent.

EXAMPLE

[0036]There will be explained how to synthesize and cure a polymer used to
form the encapsulant material 15 with reference to a working example of
the present invention. In this example, a
polymethyl(allyletherbiphenyl-pendant)siloxane given by the following
reaction formula (11) and polymethyl(allylcarbazole-pendant)siloxane
given by the following reaction formula (12) are synthesized as will be
described below.

[0037]The reaction formula (11) indicates the reaction taking place in
production of a polymethyl(allyletherbiphenyl-pendant)siloxane from a
polyhydromethylsiloxane and allyletherbiphenyl, and the reaction formula
(12) indicates the reaction taking place in production of a
polymethyl(allylcarbazole-pendant)siloxane from a polyhydromethylsiloxane
and allylcarbazole.

##STR00010##

Synthesis of Allyletherbiphenyl

[0038]First an agitator and cooling tube were set in a three-neck flask
having a capacity of 500 mL. Into the three-neck flask, there were put
12.74 g of 2-hydroxybiphenyl (70 mmol by TOKYO CHEMICAL INDUSTRY, CO.,
LTD.), 13.72 g of kalium carbonate (70 mmol), 8.5 g of allylbromide (70
mmol by TOKYO CHEMICAL INDUSTRY, CO., LTD.) and 200 g of
dimethylacetoamide (by WAKO PURE CHEMICAL INDUSTRIES, LTD.). These
ingredients were agitated at 80° C. for 10 hours. After the
agitation, clear supernatant liquid was taken and the solvent was
distilled away by an evaporator. Next, the liquid was dissolved in
toluene, washed with a NaOH aqueous solution, and then distilled under a
reduced pressure to provide a transparent and colorless liquid (of 20
mPas in viscosity at room temperature). The liquid was analyzed using an
FT-IR (Fourier Transform Infrared Spectrometer, JASCO FT/1R-460 Plus). As
a result, it was known that the liquid was a biphenylether in which the
--OH group of 2-hydroxybiphenyl was allyletherified. The liquid had a
purity of 97.5%.

Synthesis of polymethyl(allyletherbiphenyl-pendant)siloxane

[0039]First an agitator and a cooling tube were set in a three-neck flask
of 300 mL in capacity. Into the three-neck flask, there were put 100 g of
toluene, 50 mg of 2-propanol solution of chloroplatinic (of 5% by weight
in concentration of chloroplatinic), 2.2 g of polyhydromethylsiloxane
(Gelest HMS-993; 2200 in average molecular weight) and 7.6 g of
allyletherbiphenyl. Then, the mixture was heated for 20 hours in a water
bath kept at 60° C. while being agitated. The toluene solvent was
distilled away under a reduced pressure by an evaporator to provide a
transparent and colorless, viscous liquid (of 5 mPas in viscosity at room
temperature). The liquid was analyzed using the FT-IR. The analysis
showed that the Si--H peak (2171 cm-1) disappeared. Also, the liquid
was analyzed using 1H-NMR (Proton Nuclear Magnetic Resonance; Varian
300-MR). As a result, it was shown that a part of the Si--H group of
siloxane had reacted with the allyletherbiphenyl.

Hardening of the polymethyl(allyletherbiphenyl-pendant)siloxane

[0040]First an agitator and a cooling tube were set in a three-neck flask
of 300 mL in capacity. Into the three-neck flask, there were put 100 g of
toluene, 50 mg of 2-propanol solution of chloroplatinic (of 5% by weight
in concentration of chloroplatinic), 2.2 g of polyhydromethylsiloxane
(Gelest HMS-993; 2200 in average molecular weight) and 6.8 g of
allyletherbiphenyl. Then, the mixture was heated for 20 hours in a water
bath kept at 60° C. while being agitated. Next, the toluene
solvent was distilled away under a reduced pressure by an evaporator to
provide a transparent and colorless, viscous liquid. The liquid was
analyzed using the FT-IR, and the analysis proved that there existed only
a small Si--H peak (2171 cm-1). Also, the analysis showed that the
peak would not completely disappear even when the liquid was further
agitated and heated. Further it was found that heating the liquid with
addition of a polyphenylmethylsiloxane having a vinyl group at either end
thereof (Gelest PDV-03325) in 10% could result in gelling.

Synthesis of poly(allylcarbazole-pendant)siloxane

[0041]First an agitator and a cooling tube were set in a three-neck flask
of 300 mL in capacity. Into the three-neck flask, there were put 100 g of
toluene, 50 mg of 2-propanol solution of chloroplatinic (of 5% by weight
in concentration of chloroplatinic), 2.2 g of polyhydromethylsiloxane
(Gelest HMS-993; 2200 in average molecular weight) and 7.4 g of
allylcarbazole (by Nippon Distillation Kogyo). Then, the mixture was
heated for 20 hours in a water bath kept at 60° C. while being
agitated. Next, it was reprecipitated in hexane to provide a white
powder. Then, the liquid was analyzed using the FT-IR. As a result, it
was shown that the Si--H peak (2171 cm-1) disappeared. Also, the
liquid was analyzed using the 1H-NMR, and the analysis proved that a
part of the Si--H group of siloxane had reacted with the allylcarbazole.

[0042]The results of a variety of measurements made for the
poly(allyletherbiphenyl-pendant)siloxane and
poly(allylcarbazole-pendant)siloxane, synthesized as having been
described above, will be described below.

Refractive index measurement of the
poly(allyletherbiphenyl-pendant)siloxane and
poly(allylcarbazole-pendant)siloxane

[0043]An Abbe refractometer (DR-M2 by ATAGO CO., LTD.; 589 nm at
25° C.) was used to measure the refractive index of the
poly(allyletherbiphenyl-pendant)siloxane and
poly(allylcarbazole-pendant)siloxane, synthesized as above. The measured
refractive index of the allyletherbiphenyl was 1.58, while that of the
poly(allyletherbiphenyl-pendant)siloxane was 1.56. The refractive index
of allylcarbazole is 1.67, but that of the synthesized
poly(allylcarbazole-pendant)siloxane was 1.64 (measured by DSC at a glass
transition temperature Tg of 52° C.).

Transmittance Measurement of the poly(allyletherbiphenyl-pendant)siloxane

[0044]FIG. 5 shows a change of light transmittance (%) in relation to
wavelength (nm) when light is irradiated to the synthesized
poly(allyletherbiphenyl-pendant)siloxane. As shown in FIG. 5, the
measured light transmittance of the
poly(allyletherbiphenyl-pendant)siloxane was 96% for light of 460 nm in
wavelength emitted from a general-purpose royal-blue LED. That is, it can
be said that the synthesized poly(allyletherbiphenyl-pendant)siloxane is
a very transparent polymer and suitably usable as a material of the
encapsulant material 15.

[0045]Relative Light Output Measurement of the Light-Emitting Device 1
Using an Encapsulant Material Made from the
poly(allyletherbiphenyl-pendant)siloxane

[0046]Table 3 shows a total of luminous quantities measured with only the
LED chip 11, not the lens frame 14 and encapsulant material, mounted on
the light-emitting device 1 (product Nos. 1 and 2) and a total of
luminous quantities measured with the LED chip 11, lens frame 14 and
poly(allyletherbiphenyl-pendant)siloxane-made encapsulant material
mounted on the device 1. As will be known from Table 3, in case the
poly(allyletherbiphenyl-pendant)siloxane was used as the sealing
material, the relative light output was found increased by 192% on the
average over that measured with the lens frame 14 and encapsulant
material 15 not mounted on the device 1, namely, with only the LED chip
11 mounted.

[0047]Relative Light Output Measurement of the Light-Emitting Device 1
Using an Encapsulant Material Made from the
poly(allylcarbazole-pendant)siloxane

[0048]Table 4 shows a total of luminous quantities measured with only the
LED chip 11, not the lens frame 14 and encapsulant material, mounted on
the light-emitting device 1 (product Nos. 1 and 2) and a total of
luminous quantities measured with the LED chip 11, lens frame 14 and
poly(allylcarbazole-pendant)siloxane-made encapsulant material mounted on
the device 1. As will be known from Table 4, in case the
poly(allylcarbazole-pendant)siloxane was used as the sealing material,
the relative light output was found increased by 197% on the average over
that measured with the lens frame 14 and encapsulant material 15 not
mounted on the device 1, namely, with only the LED chip 11 mounted.

[0049]Namely, for the light-emitting device 1 according to this
embodiment, it is possible to provide an LED being heat-resistant and
having a high refractive index while keeping transparency by using, as
the encapsulant material, the polysiloxane having a functional group
introduced in the side chain thereof as mentioned above. More
specifically, in the structure with the high refractive-index units
introduced in the siloxane skeleton via the hydrosilylation, the light
resistance and heat resistance can be kept irrespectively of the high
refractive-index units because there are no ester bonds and hydroxy group
which will cause the polymer being turned yellow when the encapsulant
material is exposed to light and heat and the association of the high
refractive-index units is inhibited by the siloxane main chain.

[0050]Also in the light-emitting device 1 according to this embodiment,
the siloxane skeleton of the polymer leads to a lower glass transition
temperature Tg, so that it is possible to prevent the wire from being
broken and the encapsulant material from being cracked.

[0051]In the foregoing, the present invention has been described in detail
concerning certain preferred embodiments thereof as examples with
reference to the accompanying drawings. However, it should be understood
by those ordinarily skilled in the art that the present invention is not
limited to the embodiment but can be modified in various manners,
constructed alternatively or embodied in various other forms without
departing from the scope and concept thereof as set forth and defined in
the appended claims.

[0052]In the aforementioned embodiment, the light-emitting device 1
includes a single LED chip 11. However, the light-emitting device 1
according to an embodiment of the present invention may include a
plurality of LED chips in the LED device. In this case, the member 16,
encapsulant material 15, lens frame 14, etc. may be provided for each of
the plural LED chips. Alternatively, a common member 16, encapsulant
material 15, lens frame 14, etc. may be provided for all the plural LED
chips.

[0053]Also, the light-emitting device is not limited to one shown in FIG.
3 but may be constructed in various other forms without departing from
the scope and concept thereof as set forth and defined in the appended
claims.

[0054]According to an embodiment of the present invention, it is possible
to provide an optical component encapsulant material having relative high
light output, color fastness, heat resistance, and a light-emitting
device using the same.